Neurospora provides an almost unique system for exploring the relationship between the electrical properties of the plasma membrane and the operation of many charge-separating transport processes which had been predicted to occur in energy-conserving membranes, by "chemiosmotic" hypothesis for energy conservation and transport The basic purpose of continuing experiments with the system is to determine the exact current-voltage relationships for the main electrogenic (H ion) pump, H ion-dependent cotransport carriers for glucose, amino acids, and inorganic ions; and genuine "leakage" paths through the membrane. Sorting out the behavior of these systems from the total behavior of the plasma membrane requires the use of metabolic inhibitors, membrane-active antibiotics, lipid- soluble ions, and computerized digital acquisition and processing of electrophysiological data. The results should facilitate construction of physical models for the carrier-mediated transport systems, and will give limit properties which must be satisfied by the macromolecules which must be involved, and whose isolation being undertaken in other laboratories currently working on transport in the same organism.